Heat treatment apparatus

ABSTRACT

A heat treatment table is divided into two or more regions, a heater is disposed for each region. On a predetermined portion of the heat treatment table, a plurality of sensors are disposed separately each other. A relation between temperatures of the respective portions on the heat treatment table and temperatures detected by the sensors is grasped in advance, thereby enables to surmise a temperature of the respective portion of the heat treatment table from the temperature detected by the sensors. In the case of an wafer being actually treated by placing on the heat treatment table, the temperatures detected by the sensors are observed, from these detected temperatures, the temperatures of the respective portions on the heat treatment table, that is, temperatures affecting the wafer, are surmised.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat treatment apparatus such as aheater or a pre-heater to be assembled in a semiconductor manufacturingsystem for manufacturing semiconductor elements by use of aphotomechanical process, for instance.

2. Description of the Related Art

Conventionally, in a semiconductor manufacturing system which employs aphotomechanical process, various kinds of treatment units such as aresist coating unit, a drying unit, a heating unit and the like areassembled in one system. And, a string of treatments are carried outwhile transferring among these various kinds of treatment units in turn.

FIG. 12 shows a vertical cross section of a typical heat treatment unit500.

In this heat treatment unit 500, a semiconductor wafer (hereinaftersimply refers to as “wafers”) W is disposed on an upper surface of aheat treatment table 501, and the wafer W is heated by heat evolved fromthe heat treatment table 501. In this heat treatment table 501, aheating mechanism which is not shown in the figure is integrated, theheat treatment table 501 is heated by heat supplied from this heatingmechanism. On the upper surface of the heat treatment table 501, thereare disposed a plurality of small projections which are not shown in thefigure, the wafer W is disposed on the tops of these small projections,thus the lower surface of the wafer W is designed to be prevented frombeing scratched or stuck by dust due to contact between the lowersurface of the wafer W and the upper surface of the heat treatment table501. Therefore, between the lower surface of the wafer W and the uppersurface of the heat treatment table 501, minute gaps are formed, and,from the upper surface of the heat treatment table 501, heat is suppliedto the lower surface of the wafer W through a gas, for instance, anitrogen gas in the gaps. The gas heated by the heat treatment table 501and the wafer W, being smaller in its specific gravity than that of thesurrounding air of lower temperature, ascends within the heat treatmentunit 500, is collected in a cover assembly 502 disposed oppositely abovethe heat treatment table 501, and is evacuated through a piping 504connected to the top 503 of the cover assembly 502.

Now, an wafer W is liable to be affected by heat. Thus, when the heattreatment temperature goes out of its allowed range, the quality of thesemiconductor products deteriorates to lead to a lower yield, resultingin an increase of the manufacturing cost. Therefore, in such the heattreatment unit 500 as described above, a temperature sensor such as athermocouple is inserted within the heat treatment table 501,temperature control is carried out based on the temperature detectedthereby.

However, the temperature distribution of the heat treatment table is notnecessarily uniform, thus correct detection of the temperature isdifficult. To be correct, the temperatures are required to be measureddirectly of the respective parts by disposing a plurality of heaters andtemperature sensors for the respective parts. However, since manytemperature sensors are necessary, there are such problems that the(manufacturing cost of the apparatus goes up and the structure of theapparatus becomes complicated.

In addition, in such the conventional heat treatment unit 500 asdescribed above, in order to heat enough the gas between the uppersurface of the heat treatment table 501 and the lower surface of thewafer W, the temperature of the heat treatment table 501 is required tobe heated higher than the treatment temperature of the wafer W.

However, heat transmission from the heat treatment table 501 to thewafer W is not uniform, accordingly the heat tends to linger above thecenter of the wafer W, affecting a higher temperature there than thesurroundings.

As the result, the heat treatment becomes nonuniform, the quality of thesemiconductor elements formed on the wafer W tends to fluctuate, therebyproduces problems that the yield of the semiconductor elements becomeslow and the manufacturing cost of the semiconductor elements goes up.

The present invention was made to solve such problems. The objective ofthe present invention is to provide a heat treatment apparatus which iscapable of implementing a uniform heat treatment all over the wholewafer W.

Another objective of the present invention is to provide a heattreatment apparatus which is capable of carrying out an accuratetemperature control during the heat treatment of the wafer W.

SUMMARY OF THE INVENTION

The present invention was made to solve such problems. Still anotherobjective of the present invention is to provide a heat treatmentapparatus which is capable of controlling accurately the temperaturewith a small number of temperature sensors, accordingly capable ofcarrying out a uniform heat treatment all over the whole wafer W.

Further, still another objective of the present invention is to providea heat treatment apparatus which is capable of carrying out an accuratetemperature control during the heat treatment of the wafer W.

A heat treatment apparatus of the first invention, comprises:

a heat treatment table thereon a substrate to be treated is disposed;

two or more heaters for heating the each areas of the heat treatmenttable divided into two or more areas;

at least a sensor detecting the temperature of the predetermined area ofthe heat treatment table;

a means for predicting the temperatures of the each areas of the heattreatment table based on the detected temperature; and

a means for controlling the output of the each heaters based on thetemperatures predicted for the each areas so that the temperature of thewhole heat treatment table becomes uniform.

Further, another embodiment of a heat treatment apparatus of the firstinvention, comprises:

a heat treatment table thereon a substrate to be treated is disposed;

two or more heaters for heating the each areas of the heat treatmenttable divided into two or more areas;

at least one sensor for detecting the temperature of the predeterminedarea of the heat treatment table;

a means for predicting an amount of heat to be supplied to the each areaof the substrate to be heat treated based on the detected temperatures;and

a means for controlling the output of the each heaters based on thepredicted amount of heat so that the amount of heat to be supplied tothe substrate to be treated becomes uniform.

The heat treatment apparatus of the second invention comprises a heatingmeans for heating the lower surface of the substrate to be treated, anda means for cooling the gas heated to the predetermined temperature ormore by the heating means above the substrate to be treated.

The heat treatment apparatus involving another embodiment of the secondinvention comprises a heating means for heating a lower surface of asubstrate to be treated, a means for evacuating the gas heated by theheating means from an above portion of the substrate to be treated, ameans for detecting the temperature affecting on the substrate to betreated, and a means for cooling, based on the detected temperature, thegas passing the above portion of the substrate to be treated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing an entire structure of acoating/developing system involving the embodiment of the firstinvention.

FIG. 2 is a front view of a coating/developing system involving theembodiment of the first invention.

FIG. 3 is a rear view of a coating/developing system involving theembodiment of the first invention.

FIG. 4 is a plan view showing a constitution of a heat treatment unitinvolving the embodiment of the first invention.

FIG. 5 is a cross-section of a heat treatment unit involving theembodiment of the first invention.

FIG. 6 is a plan view of a heat treatment table involving the embodimentof the first invention.

FIG. 7 is a vertical cross section of a heat treatment table involvingthe embodiment of the first invention.

FIG. 8 is a block diagram showing a control system of a heat treatmentunit involving the embodiment of the first invention.

FIG. 9 is a vertical cross section of a heat treatment unit involvinganother embodiment of the first invention.

FIG. 10 is a plan view showing a state seen from the lower side of acover assembly and involving another embodiment of the first invention.

FIG. 11 is a block diagram illustrating a control system of a heattreatment unit involving another embodiment of the first invention.

FIG. 12 is a vertical cross section of a conventional heat treatmentunit.

FIG. 13 is a vertical cross section of a cover assembly involving theembodiment of the second invention.

FIG. 14 is a plan view of a state seen from the lower side of a coverassembly and involving the embodiment of the second invention.

FIG. 15 is a vertical cross section showing schematically a structure inthe neighborhood of a thermal surface plate involving the embodiment ofthe second invention.

FIG. 16 is a block diagram showing a control system of a heat treatmentunit involving the embodiment of the second invention.

FIG. 17 is a diagram showing relation between the temperature of heattreatment of a heat treatment unit, temperature of wafer W, andtemperature of jacket involving the embodiment of the second invention.

FIG. 18 is a vertical cross section of a cover assembly involving theembodiment of the third invention.

FIG. 19 is a plan view of a state seen from the lower side of a coverassembly and involving the embodiment of the third invention.

FIG. 20 is a vertical cross section showing schematically a structure ofthe surroundings of a thermal surface plate involving the embodiment ofthe third invention.

FIG. 21 is a block diagram illustrating a control system of a heattreatment unit involving the embodiment of the third invention.

FIG. 22 is a diagram showing relation between temperature of heattreatment of the heat treatment unit, temperature of wafer W, andtemperature of heater involving the embodiment of the third invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT EXAMPLE 1

In the following, the detailed description of the embodiments of thepresent invention will be given based on the drawings.

Incidentally, the scope of the present invention should not be construedto be restricted to that of the following embodiments.

FIG. 1 is a plan view showing the entire of a coating/developing system1 of semiconductor wafers (hereinafter simply refer to as “wafer”) whichis provided with a resist coating unit (COT) involving one embodiment ofthe present invention.

In this coating/developing system 1, a cassette station 10 which carriesin/out wafers, subjects to be treated, from the outside/inside by awafer cassette CR by a plurality of pieces, that is, by a unit of 25pieces for instance, or which carries in/out the wafers W to/from thewafer cassette CR, a treatment station 11 in which various kinds oftreatment units of sheet-fed type which carry out the predeterminedtreatments to the respective wafers during the coating/developmentprocess are disposed multistage, and an interface portion 12 whichdelivers the wafers W between an exposure device (not shown in thefigure) disposed adjacent to the treatment station 11, are connectedintegrally.

In this cassette station 10, at the place of a positioning projection 20a on a cassette stage 20, a plurality of pieces, up to 4 pieces forinstance, of wafer cassettes CR are disposed directing the inlet/outletof the respective wafers towards the treatment station 11 side in oneline in X direction (the up and down direction in FIG. 1). And a wafercarrier 21 capable of moving in the direction where the cassettes arearranged (X direction) and in the direction where the wafers Waccommodated in the wafer cassette CR are arranged (Z direction;vertical direction) makes a selective approach to the respective wafercassette CR.

This wafer carrier 21 is capable of rotating freely in θ direction andalso can make an approach to an alignment unit (ALIM) disposed to themultistage unit portion of the third treatment unit group G₃ on thetreatment station 11 side which will be described later or an extensionunit (EXT).

To the treatment station 11, a main wafer carrying mechanism 22 ofvertically carrying type provided with a wafer carrier is disposed, theentire treatment units are disposed multistage in the surroundingthereof in one set or a plurality of sets.

FIG. 2 is a front view of the aforementioned coating/developing system1.

In the first treatment unit group G₁, two sets of spinner type treatmentunit for carrying out the predetermined treatment while holding an waferW on a spin chuck in a cup CP, for instance a resist coating unit (COT)and a developing unit (DEV), are stacked in two stages from the bottom.In the second treatment unit group G₂, two sets of treatment unit ofspinner type, for instance a resist coating unit (COT) and a developingunit (DEV) are stacked in two stages from the bottom. These resistcoating units (COT), since the waste liquid of the resist liquid istroublesome from the mechanism and maintenance points of view, arepreferable to be disposed at the lower stage. However, as the needarises, they can be disposed appropriately on the upper stage.

FIG. 3 is a rear view of the aforementioned coating/developing system 1.

In the main wafer carrying mechanism 22, inside a cylindrical supporter49, an wafer carrier 46 is equipped movable freely in the up and downdirection (Z direction). The cylindrical holder 49 is connected to arotating axis of a motor (not shown in the figure), and, by the rotatingdriving force of this motor, rotates together with the wafer carrier 46with the rotating axis as a center, thereby the wafer carrier 46 is madecapable of rotating freely in the θ direction. Incidentally, thecylindrical supporter 49 may be constituted to be connected to anotherrotating axis (not shown in the figure) which is rotated by the motor.

To the wafer carrier 46, a plurality of holding members which aremovable freely in the forward and backward direction of a carrier base47 are disposed, these holding members 48 enable delivery of the wafersbetween the respective treatment units.

Further, as shown in FIG. 1, in this coating/developing system 1, 5groups of treatment unit G₁, G₂, G₃, G₄, and G₅ are possible to bedisposed, multistage units of the first and the second groups oftreatment unit G₁ and G₂ are disposed in a front (this side in FIG. 1)side of the system, a multistage unit of the third group of treatmentunit G₃ is disposed adjacent to the cassette station 10, a multistageunit of the fourth group of treatment unit G₄ is disposed adjacent to aninterface portion 12, and a multistage unit of the fifth group oftreatment unit G₅ can be disposed on the rear side.

As shown in FIG. 3, in the third group of treatment unit G₃, an oventype treatment unit for carrying out the predetermined treatment whileholding the wafer W on a holding stage (not shown in the figure), forinstance, a cooling unit (COL) for cooling, an adhesion unit (AD) forcarrying out a so called hydrophobic treatment in order to heightenfixing property of the resist, an alignment unit for aligning (ALIM), anextension unit (EXT), a pre-baking unit (PREBAKE) for carrying out heattreatment preceding the exposure and a post-baking unit (POBAKE) forcarrying out heat treatment after exposure are stacked in turn, in eightstages for instance, from the bottom. Even in the fourth group oftreatment unit G₄, an oven type treatment unit, for instance a coolingunit (COL), an extension cooling unit (EXTCOL), an extension unit (EXT),a cooling unit (COL), a pre-baking unit (PREBAKE) and a post-baking unit(POBAKE) are stacked in turn, in eight stages, for instance, from thebottom.

By disposing the cooling unit (COL) and extension cooling unit (EXTCOL)of low treatment temperature at the lower stage as described above, andby disposing the pre-baking unit (PREBAKE), post-baking unit (POBAKE)and adhesion unit (AD) of higher treatment temperature at the upperstage, thermal interference between units can be made small. Naturally,random multistage disposition may be adopted.

As shown in FIG. 1, in the interface portion 12, the depth direction (Xdirection) possesses the dimension identical with the aforementionedtreatment station 11, however the breadth direction (Y direction)possesses a smaller size. Or the front portion of this interface portion12, a portable pickup cassette CR and a fixed buffer cassette BR aredisposed in two stages, whereas, on the rear portion, a peripheryexposing device 23 is disposed, further, in the central portion, anwafer carrier 24 is disposed. This wafer carrier 24 makes an approach toboth cassettes CR and BR, and the periphery exposing apparatus 23 bymoving in the X direction and Z direction.

The wafer carrier 24 is capable of rotating freely even in θ direction,and can make an approach to an extension unit (EXT) disposed to themultistage unit of the fourth group of treatment unit G₄ on thetreatment station 11 side, or an wafer delivery table (not shown in thefigure) on the side of the adjacent exposing device.

Further, in the coating/developing treatment system 1, as describedabove, even to the rear side of the main wafer carrying mechanism 22, amultistage unit of the fifth group of treatment unit G₅ shown by thedotted lines in FIG. 1 may be disposed, however, the multistage unit ofthe fifth group of treatment unit G₅ can be moved in Y direction along aguide rail 25. Therefore, even in the case of the multistage unit of thefifth group of treatment unit G₅ being disposed as shown in the figure,by travelling along the guide rail 25, a space can be secured.Therefore, a maintenance operation to the main wafer carrying mechanism22 can be carried out readily from the back.

Next, with reference to FIG.4 and FIG. 5, constitutions and operationsof the heat treatment unit such as baking units (PREBAKE) and (PROBAKE)and a cooling unit (COL) and (EXTCOL) which are included in themultistage units of the third and fourth groups G₃ and G₄ in thetreatment station 11 will be described.

FIG.4 and FIG. 5 are a plan view and a cross-sectional view showing aconstitution of a heat treatment unit involving the present embodiment.Incidentally, in FIG. 5, a horizontal separating plate 55 is omitted foran illustration.

A treatment room 50 of this heat treatment unit is formed of both sidewalls 53 and the horizontal separating plates 55, and the front side(the side of main wafer carrying mechanism 24) and the rear side of thetreatment room 50 are openings 50A and 50B, respectively. At the centralportion of the separating plate 55, a circular opening 56 is formed,inside this opening 56, a disc like heat treatment table 58 is disposedas a stage for setting an wafer W.

To this heat treatment table 58, three holes 60, for instance, arebored, inside the each hole 60, a supporting pin 62 is pierced withplay, and, when a semiconductor wafer W is loaded or unloaded, the eachsupporting pin 62 projects or ascends above the front surface of theheat treatment table 58, thereby delivery of the wafer W is carried outbetween the holding member 48 of the main wafer carrying mechanism 22.

On the exterior periphery of the heat treatment table 58, a shutter 66consisting of a belt plate of ring shape in which many air holes 64 areformed with 2° apart in a circumference direction is disposed. Thisshutter 66 normally stays receded at a position below the heat treatmenttable 58, however, during heat treatment, ascends to the position higherthan the upper surface of the heat treatment table 58 as shown in FIG.5, thereby forms a side wall of ring shape between the heat treatmenttable 58 and the cover assembly 68, thereby a down-flow inert gas,nitrogen gas for instance, sent in from a gas supplying system not shownin the figure, can be flowed in uniformly in the circumference directionfrom the air holes 64.

At the central portion of the cover assembly 68, an exhausting opening68 a is disposed to evacuate the gas evolved from the surface of thewafer W during heat treatment, and, to this exhausting opening 68 a, anexhausting pipe 70 is connected. This exhausting pipe 70 communicateswith a duct 53 (or 54) of the front side of the apparatus (the side ofthe main wafer carrying mechanism 22) or a duct not shown in the figure.

Below the separating plate 55, a machine room 74 is formed out of theseparating plate 55, both side walls 53 and a bottom plate 72, therein,a heat treatment table holding plate 76, a shutter arm 78, a supportingpin arm 80, a cylinder 82 for driving the shutter arm going up and down,and a cylinder 84 for driving the supporting pin arm going up and downare disposed.

As shown in FIG. 4, on a surface position of the heat treatment table 58thereon the exterior periphery of the wafer W is placed, a plurality ofpieces, four pieces for instance, of supporting projections 86 forguiding the wafer W are disposed.

Further, there are a plurality of small projections, which are not shownin the figure, on a part, thereon an wafer W is placed, of a uppersurface of the heat treatment table 58, and the lower surface of thewafer W is placed on the tops of these small projections. Accordingly,there are formed minute spaces between the lower surface of the wafer Wand the upper surface of the heat treatment table 58, thereby the lowersurface of the wafer W is prevented from touching directly with theupper surface of the heat treatment table 58, thus even in the case ofthere being dust and the like, the wafer W is prevented fromcontamination or scratching taking place.

In addition, as will be described later, there are disposed a pluralityof heaters inside the heat treatment table 58, by heating these heaters,the heat treatment table 58 can be maintained at the predeterminedtemperature.

FIG. 6 is a plan view depicting schematically a structure of the heattreatment table 58 involving an embodiment corresponding to the firstinvention, and FIG. 7 is a vertical cross section depictingschematically a structure of the same heat treatment table 58.

As shown in FIG. 6, this heat treatment table 58 is formed of fiveregions of from P1 through P5 of doughnut shape. These regions P1through P5 are formed concentric, and, inside of P1 through P5, thereare disposed heaters H1 through H5 which are independent each other, forinstance, Nichrome heaters (not shown in the figure) are formed in thedoughnut shape as identical as the respective regions P1 through P5. Theheaters are wired independently each other, thereby the amount of heatto be supplied to the respective regions of P1 through P5 can becontrolled independently each other.

To the second region P2 and the fourth region P4 from the outside of theheat treatment table 58, holes for attaching sensors are bored vertical,and into these holes, the sensor S1 and sensor S2 are attached vertical,respectively. These sensors detect the temperature distribution in thehorizontal direction of the heat treatment table 58.

Further, from the direction of the right side surface in FIG. 6 of theheat treatment table 58, there are bored holes of the horizontaldirection in parallel at two places up and down, these holes reach up tothe midway of the region P2 piercing through the region P1.

As shown in FIGS. 6 and 7, also to these holes, sensors S3 and S4 areattached. These sensors S3 and S4 detect the temperature distribution inthe vertical direction of the heat treatment table 58.

FIG. 8 is a block diagram illustrating a control system of a heattreatment unit involving the present embodiment.

As shown in FIG. 8, inside the respective regions of P1 through P5 ofthe heat treatment table 58, there are disposed heaters H1 through H5,respectively. These heaters H1 through H5 are connected to a controlunit 90, by this control unit 90 their output is controlled. Further,the sensors S1 through S4 are also connected to this control unit 90,thereby the temperatures of the respective parts of the heat treatmenttable 58 are recognized by the control unit 90.

Next, the way how to control the heat treatment unit involving thepresent embodiment will be described.

In the heat treatment unit involving the present embodiment, thetemperatures of the predetermined parts of the heat treatment table 58are detected, from these temperatures the temperature distribution ofthe entire heat treatment table 58 is surmised. Then, based on thissurmised result, the output of the heaters H1 through H5 is controlledto prevent the thermal non-uniformity from occurring.

In the concrete, concerning the temperature distribution in thehorizontal direction of the heat treatment table 58, the temperaturedistribution of the entire heat treatment table is surmised from thetemperatures detected by the sensor S1 which is disposed in the regionP2 second from the periphery of the heat treatment table 58 and thesensor S2 which is disposed in the region P4 fourth from the peripheryof the heat treatment table.

For instance, when the same electric power is supplied to the heaters H1through H5, in the case of the heat treatment table 58 having a tendencythat the temperature is the minimum at the region P1, and as goes insideas P2, P3, . . . , goes up to the maximum at the region P5, thecorrespondence between the respective temperatures of the regions P2 andP4 where the sensors S1 and S2 are disposed and other regions P1, P3 andP5 than these is obtained from the measured values or theoreticalvalues. And, by formulating a table which enables to specify therespective temperatures of the regions P1, P3 and P5 throughspecification of the temperatures of the sensors of S1 and S2 and thepower supplies to the heaters of H1 through H5, this is memorized in thememory elements of the control unit.

Similarly, also in the case of the power supply to the heaters H1through H5 being varied, the similar table is formulated, therebyenables to specify the respective temperatures of the region P1, P3 andP5 by specifying the temperatures of the sensors S1 and S2 and therespective power supplies tD the heaters H1 through H5.

Thus, from the temperature signals detected by the sensors S1 and S2 andthe power supply signals to the heaters H1 through H5, the temperaturedistribution of the entire heat treatment table 58 including the regionsP1, P3 and P5 is surmised.

Next, based on the surmised temperature distribution of the entire heattreatment table 58, the electric power to be supplied to the each heaterof H1 through H5 is adjusted to control the output of the each heater ofH1 through H5 so that the temperature of the entire heat treatment table58 becomes uniform.

In the concrete, based on the aforementioned table, the power supply tothe each heater is adjusted to control the output of the each heater ofH1 through H5 so that the regions P1 through P5 become uniform.

For instance, as mentioned above, in the case of the temperature of theregion P1 being the minimum and, as goes inside as P2, P3, . . . , thetemperature becoming higher to the maximum at the region P5, the outputof the each heater of the heaters H1 through H5 is controlled to cancelsuch a thermal non-uniformity. That is, the output of the heater H1 ismade high, that of the heater H5 is made low, and the output of theheaters H2 through H4 intervening them is made incline to connectcontinuously from the heater H1 to the heater H5. These output values ofthe heaters H1 through H5 also are obtained based on the aforementionedtable by use of the temperatures of the regions P2 and P4 as theindicators.

Further, in the heat treatment unit involving the present embodiment,also in the vertical direction of the heat treatment table 58, thesensors S3 and S4 are disposed. And, based on the temperatures detectedby these sensors S3 and S4, the temperature distribution in the verticaldirection of the entire heat treatment table 58 is surmised, thereby thetemperature of the heat treatment table 58 is administered.

In the concrete, with the sensors S3 and S4, the temperatures in thevertical direction of the region P2 are detected. On the other hand, thecorrespondence between the detected temperatures of the sensors S3 andS4 and the temperature distribution in the vertical direction of theeach region of the P1 through P5 of the heat treatment table 58, and therelation with the output of the each heater of H1 through H5 areobtained in advance from the measured values or the theoreticallycalculated values, they are memorized as identically as the above in thememory part of the control unit.

Then, with the temperatures detected by the sensors S3 and S4 at twoplaces, high and low, of the region P2 as the indicators, thetemperature distribution of the surface of the heat treatment table 58is surmised. That is, from the temperatures of the region P2 detected bythe sensors S3 and S4, by use of the aforementioned table, thetemperatures in the neighborhood of the surface of the other region P1and P3 through P5 are surmised. Then, in the case of the surfacetemperature of each region of the regions P1 through P5 being irregular,the output of the heaters H1 through H5 is controlled by use of theaforementioned tables so that the surface temperature of the heattreatment table 58 becomes uniform and adequate.

Next, operation in the case of this heat treatment unit being employedas a baking unit (PREBAKE) and cooling unit (COL) will be described inthe followings.

First, from inside an wafer cassette CR which is set on a stage 20, anwafer W is pulled out by an wafer carrier 21, then the wafer W isdelivered from the wafer carrier 21 to a main wafer carrying mechanism22. The main wafer carrying mechanism 22 carries the delivered wafer Winto a resist coating unit (COT) and sets, here resist coating iscarried out on the wafer W. Then, the wafer W is pulled out from insidethe resist coating unit (COT) by the main wafer carrying mechanism 22,carried into the aforementioned heat treatment unit, and set on the heattreatment table 58.

On the other hand, at the same time with power input to the heattreatment unit, power is began to be input to the heaters H1 through H5within the heat treatment table 58. When the temperature of the heattreatment table 58 becomes stable after the predetermined time periodelapsed, the control unit 90 starts to operate to adjust the output ofthe heaters H1 through H5.

That is, with the sensors S1 and S2 disposed at the regions P2 and P4,the temperature adjustment of the horizontal direction of the heattreatment table 58 is carried out, thereby the heat treatment table 58is controlled so that the temperature is maintained adequate anduniform.

For instance, in the case of the temperature being low in the region P1,and, as the region goes inside as P2, P3, . . . , becoming high to bethe maximum at the region P5, the output of the heater H1 is made high,and, as the heater goes inside as H2, H3, . . . , the output is made lowto be the minimum at the heater H5.

On the contrary, in the case of the temperature being high at the regionP1, and, as the region goes inside as P2, P3, . . . , becoming low to bethe minimum temperature at the region P5, the output of the heater H1 ismade low, and, as the heater goes inside as H2, H3, . . . , the outputis increased to be the maximum at heater H5.

Similarly, in the case of the temperatures of the regions P1 and P5being low and the these of the regions P2 through P4 being high, whereasthe output of the heaters H1 and H5 are made high, the output of theheaters H2 through H4 are made low. Here, for the output value of theeach heater of the aforementioned each case, the most adequate value areobtained based on the aforementioned tables, the output value beingadjusted to these values.

Further, also as to the temperature distribution in the verticaldirection of the heat treatment table 58, similarly, based on thetemperature detected from the sensors S3 and S4 and the aforementionedtable, the temperature distribution on the surface of the heat treatmenttable 58 is surmised, thereby the output of the heaters H1 through H5 iscontrolled so that the temperature of the entire surface of the heattreatment table 58 becomes adequate and uniform.

Incidentally, in this embodiment, by controlling only the output of theheaters H1 through H5, the temperature control of the heat treatmenttable 58 is carried out, however, by other method than this, forinstance, by controlling the gas flow rate of the gas supply systemwhich supplies a gas such as a nitrogen gas from the side direction ofthe heat treatment table 58, the temperature control of the heattreatment table 58 can be carried out.

Thus, in the heat treatment unit involving the present embodiment,whereas the heat treatment table is divided into a plurality of regionsto dispose a heater for every region, the sensors detecting thetemperatures of the heat treatment table are disposed only for thepredetermined parts. On the other hand, the thermal correspondence as tothe heat transmission state between the region where the sensors aredisposed and other parts of the heat treatment table than these areobtained from the measured values or the theoretical values to memorizein the memory part of the control unit. When the temperature control ofthe heat treatment table is actually carried out, for the predeterminedparts, the temperatures are actually detected by the sensors, and, forthe other parts than these, the temperatures are obtained by surmisingfrom the data of the thermal correspondence memorized in the memorypart.

In the case of, as the result of this surmise, the surface temperatureof the heat treatment table being expected to be non-uniform, the outputof the heaters is controlled based on the aforementioned data so thatthe temperature of the heat treatment table is adequate and uniform.

Thus, in the heat treatment unit involving the present embodiment, thesensors are disposed only to the predetermined parts, and other partsthan these are constituted so that the temperature distribution issurmised with the mathematical method by use of the measured values ortheoretical values. Therefore, the temperature control of the heattreatment table can be carried out with a smaller number of sensorsagainst a plurality of heaters.

Further, in the heat treatment unit involving the present embodiment, inthe case of, from the above surmised results, the thermal irregularitybeing liable to occur as to the temperature distribution of the heattreatment table, the output of the heaters is controlled based on thedata of the thermal correspondence so that this thermal irregularity iscancelled. Therefore, the temperature control can be carried out withhigh accuracy.

Incidentally, the present invention is not restricted to the content ofthe aforementioned embodiments.

For instance, though, in the aforementioned embodiment, the temperaturedistribution of the entire heat treatment table is surmised from thetemperatures detected for the predetermined parts of the heat treatmenttable, by surmising further the heat amount affecting the wafer W placedon the heat treatment table, the heaters can be controlled so that theamount of heat affecting the wafer W is made uniform.

Further, in the above embodiments, the heat treatment table is dividedinto a plurality of concentric regions, and a heater formed in doughnutshape is incorporated in every region. However, the heat treatment tablecan be divided in the diameter direction or in various forms such as asector form heater or the like.

Further, also as to the number of the sensor, only one sensor can bedisposed or the sensors of the same number as that of the heater or morecan be disposed.

Further, in the above embodiments, description is carried out of thecoating/developing system 1 of the wafer W as an example, however, thepresent invention can be applied also to the treatment apparatus otherthan this, for instance, an LCD substrate treatment apparatus and thelike.

EXAMPLE 2

Next, another embodiment involving the first invention will bedescribed.

Incidentally, the parts repeating the aforementioned example 1 will beomitted from the following description.

FIG. 9 is a vertical cross section of the heat treatment table 158 andcover assembly 168 of the heat treatment unit involving the presentembodiment, and FIG. 10 is a plan view showing a state seen from thebottom of the cover assembly 168.

As shown in FIG. 9, on a wall surface 168 b formed conical on the lowersurface side of the cover assembly 168, upper heaters of sector shape h1through h20 are disposed. As shown in FIG. 10, these upper heaters h1through h20 are disposed in such a manner that the five concentriccircles, large and small, are divided into four, respectively, on thewall surface 168 b.

FIG. 11 is a block diagram showing a heating system of the heattreatment unit involving the present embodiment. As shown in FIG. 11,for each upper heater of h1 through h20, wiring is given independentlyeach other, by the control unit 190 thereto each heater is connected,the operation or the amount of heat of evolution thereof can becontrolled.

In the heat treatment unit involving the present embodiment, in additionto the heat treatment table 158 of the utterly identical structure asthat of the heat treatment table 58 involving the aforementioned firstembodiment, a cover assembly 168 thereon the upper heaters h1 throughh20 are disposed is given.

In this heat treatment unit, from the temperatures of the regions P11and P12 which are detected by the sensors S11 and S12 disposed to theregions P12 and P14 of the heat treatment table 158 and the output ofthe respective heaters H11 through H15, whether the temperaturedistribution is adequate or not, or uniform or not, is judged.

That is, as identical as the aforementioned first embodiment, from thethermal correspondence of the each regions of the heat treatment tablewhich is memorized in the memory part of the control unit 190, thetemperature distribution of the entire heat treatment table 158 issurmised, thereby whether the state of the temperature distribution isadequate or not, uniform or not, is judged.

And, in the case of the temperature distribution being judged to beinadequate, and the thermal non-uniformity being judged to be present,in order to cancel this thermal non-uniformity, the heaters H11 throughH15 are controlled. At the same time, the amounts of heat of evolutionof the upper heaters h1 through h20 disposed on the lower surface of thecover assembly 168 are controlled to cancel the thermal non-uniformity.

For instance, in the case of the periphery portion of the exteriorcircumference of the heat treatment table being low in its temperature,the amount of the heat of evolution of the upper heaters h17 through h20on the side of the periphery of the exterior circumference is increased,and in the case of there occurring partly the portion of lowertemperature, the amount of the heat of evolution of the upper heaterspositioning immediately above those portions is increased to accomplishthe uniform heat treatment of the wafer W.

Further, in the case of the cover assembly 168 involving the presentembodiment being adopted, the amount of the heat of evolution of theheat treatment table 158 is controlled so that the temperature becomes alittle bit lower than that of the heat treatment of the wafer W, on theother hand, the amount of the heat of evolution of the upper heaters h1through h20 is controlled so as to make the temperature higher than thetemperature of heat treatment of the wafer W, thereby the temperaturegradient is formed such that the temperature varies vertically towardthe upper direction from a low temperature to a high temperature. Bycarrying out the heat treatment like this, the thermal convection can beprevented from occurring above the neighborhood of the center of thewafer W. Thus, an effect characteristic to the present embodiment suchthat the control of the temperature of the heat treatment can be carriedout readily is obtained.

As described above in detail, according to the first invention, whereasthe heaters are disposed on the two or more regions, respectively, whichare formed by dividing the heat treatment table, the sensors aredisposed on the predetermined positions of the heat treatment table.Based on the temperatures detected by these sensors, the temperature ofthe each position of the heat treatment table is surmised. Therefore,the temperature control can be carried out with a small number ofsensors.

Further, based on thus surmised temperature, the output of the eachheater is controlled so that the temperature of the entire heattreatment table becomes uniform. Thus, all over the heat treatmentplate, the uniform heat treatment can be carried out.

With an arithmetic unit, based on the temperature detected above, if thetemperature of the each position of the heat treatment table is surmisedmathematically, the temperature control during heat treatment of thesubstrate to be treated can be carried out with high accuracy.

In the case of a plurality of the upper heaters which are disposeddivided concentric being disposed above the heat treatment table, on thesurface, opposing to the heat treatment table, of the cover assemblywhich is disposed opposite to the heat treatment table, since theheating is carried out from above and below the wafer, heatingefficiency is good and the uniform heat treatment can be carried out.

Further, by setting the temperature of the upper heater side at thehigher temperature with respect to the lower heater, or by controllingthe lower heaters or upper heaters so as to cancel the thermalunbalance, the temperature control during heat treatment of thesubstrate to be treated can be carried out with high accuracy.

Further, by disposing the respective heaters concentric on the heattreatment table, with respect to the diameter direction of the heattreatment table in which direction the thermal non-uniformity tends tooccur, a more delicate temperature control can be carried out, thus allover the substrate to be treated, the uniform heat treatment can becarried out.

Further, by disposing the sensors in one line in the diameter directionof the heat treatment table, a small number of the sensors can realizean accurate temperature control.

Further, by disposing the sensors in the thickness direction of the heattreatment table, the time lag due to the thermal transmission in thethickness direction can be readily corrected, thereby management of thetemperature of heat treatment or the temperature control during the heattreatment of the substrate to be treated can be carried out with highaccuracy.

EXAMPLE 3

FIG. 13 is a vertical cross section of a cover assembly 268 involvingone embodiment corresponding to the second invention, and FIG. 14 is aplan view showing a state seen from the bottom side of the coverassembly 268. As shown in FIG. 13, on the lower surface side of thecover assembly 268, a conical concave portion 168 b is formed, and atthe summit of the cone, an exhaust outlet 268 a is disposed, and a lowerend of an exhausting pipe 270 is connected to this exhaust outlet 268 a.The other end side of the exhausting pipe 270 is connected to a notshown exhausting system, the heating gas (nitrogen gas) which is heatedby the thermal surface plate and went up is collected by the conicalconcave portion 268 b, and evacuated through the exhaust outlet 268 aand exhausting pipe 270.

On the central portion of the conical concave 268 b, a through hole 268c is disposed, and to this through hole 268 c, a jacket for cooling agas (hereinafter refers simply as “jacket”) 290 is attached.

This jacket is a cooler for cooling the heating gas (nitrogen gas) whichis heated by the thermal surface plate 258 and ascended the spacebetween the thermal surface plate 258 and the cover assembly 268. Thejacket 290 has an appearance of a disc in the center of which theexhaust outlet 268 a is bored, the upper surface thereof is a plane,and, on the lower surface thereof, the conical concave 268 b is formed.The size of its diameter is nearly equal with that of the through hole268 c of the cover assembly 268, and that is designed just to beaccommodated in the through hole 268 c.

The jacket 290 is made out of materials of high thermal conductivitysuch as light alloys of aluminum or copper, and inside thereof a path291 for circulating a coolant is formed.

In the jacket 290 involving the present embodiment, as shown in FIG. 14,the circulation path 291 has a shape formed in spiral with the exhaustoutlet 268 a as its center, at the both ends of the circulation path291, pipes 292, 293 for letting in or out the coolant are connected. Theother end sides of these pipes 292, 293 are connected to a coolantsupplier 294, and the coolant cooled to the predetermined temperature bythis coolant supplier 294 is circulated inside the circulation path 291through the pipes 292 and 293.

Incidentally, in the jacket 290 of the present embodiment, there isexplained a method in which the coolant is circulated inside the jacket,however, one in which no coolant is used, for instance, air coolingtype, or an electrical one employing a Peltier element can be employed.

FIG. 15 is a vertical cross section showing schematically a structure ofa thermal surface plate 258 involving the present embodiment and itsneighborhood. As shown in this FIG. 15, the inside of the thermalsurface plate 258 forms a sealed cavity 258 a, and, on a part of thebottom portion, a reservoir 258 b of heating medium of which the crosssection is formed in a V character shape is disposed. Within thereservoir 258 b of the heating medium, a heater 293 made out of Nichromewire or the like is disposed in a direction perpendicular to the planeof the paper of FIG. 15, and to this heater 293, electric power issupplied from an electric power source 295 controlled by a control unitnot shown in the figure.

When the power is supplied to the heater 293 from the electric powersource 295, the heater 293 starts to evolve heat, and the heating mediumreserved in the reservoir 258 b of heating medium through condensationis heated by the heater 293. The heated heating medium isvaporized/evaporated to circulate inside the cavity 258 a. When thevapor of the heating medium collides the cooled part inside the cavity258 a, the vapor of the heating medium gives the amount of heat to thiscooled portion, at the same time, is condensed to liquefy. The amount ofheat given at this time from the heating medium to the thermal surfaceplate 258 is the heat of vaporization of the heating medium, beingdetermined by the kind of the heating medium. Therefore, when a sequenceof a cycle from the vaporization of the heating medium to condensationthereof becomes stable to establish a stable state, the temperature ofthe thermal surface plate can be maintained at the almost constanttemperature.

Upon the gas (nitrogen gas) of room temperature being sent from the sidedirection of the thermal surface plate 258 maintained at a constanttemperature through an airhole 301, the gas is heated at the surface ofthe thermal surface plate 258 to be the heating gas, and due tocollision of the heating gas against the wafer W disposed on the thermalsurface plate 258, the amount of heat is supplied to the wafer W.

FIG. 16 is a block diagram illustrating a control system of a heattreatment unit involving the present embodiment. As shown in FIG. 16, inthe heat treatment unit involving the present embodiment, an electricpower supply 295 which supplies the electric power to the thermalsurface plate 258 and a coolant supplier 294 are connected to a controlunit 296. To this control unit 296, there are further connected a sensorS11 which detects the temperature of the gas (nitrogen gas) in theneighborhood of the center of the lower surface of the jacket 290, and asensor S12 which detects the temperature of the wafer W disposed on thethermal surface plate 258. The control unit 296, based on thetemperature of the heating gas and the temperature of the wafer Wdetected by these sensors S11 and S12 respectively, controls the thermalsurface plate 258 and the jacket 290.

For the sensors S11 and S12, the various kinds of known temperaturesensors can be employed appropriately, however, in order to detect thetemperature of the wafer W, a sensor which can detect the temperature ina non-contact state such as a sensor of a mechanism which detects thetemperature from the radiated infra-red light or the like, for instance,is preferable.

Further, for the temperature of the thermal surface plate 258, asidentical as the aforementioned jacket 290 and the wafer W, a sensor isdisposed to detect directly the temperature, and the detectedtemperature can be sent to the control unit 296, however, thetemperature of the thermal surface plate 258 can be controlled from thetemperature of the heating medium of the power supply 295 or thesupplied power.

Next, a method for controlling the heat treatment unit involving thepresent embodiment will be described.

The thermal surface plate 258 is controlled to maintain a constanttemperature a little bit higher than that of the heat treatment of thewafer W.

As described above, the temperature of the thermal surface plate 258 iscontrolled based on a temperature sensor (not shown in the figure)disposed exclusively or the supplied power from the electric powersupply 295.

The temperature actually affecting the wafer W which is exposed to theheat treatment is detected by the sensor 12.

The gas (nitrogen gas) heated by the thermal surface plate 258 ascendsup and gathers in the neighborhood below the exhaust outlet 268 a of thejacket 290, accordingly, by the sensor S11 disposed in the neighborhoodthereof, the temperature of the heating gas can be detected.

In the case of this temperature being higher than the predeterminedtemperature, together with adjusting the temperature of the thermalsurface plate 258, the coolant supply 294 is operated to circulate acold coolant inside the jacket 290, thereby cools the overheated gas(air or an inert gas such as a nitrogen gas or the like). The gas cooledhere becomes high in specific gravity and descends to collide theneighborhood of the center of the wafer W which is liable to beoverheated, thereby preventing this part from being overheated.

On the other hand, in the case of the wafer temperature being liable toget lower than the temperature necessary for the heat treatment, thecoolant supply 294 is ceased in operation or lowered in its output,thereby overcooling is prevented from occurring. Further, thetemperature of the thermal surface plate 258 is adjusted as thenecessity arises, thereby the temperature affecting the wafer W can beprevented from lowering.

In general, it is known that, when the jacket 290 is operated in a statewhere the thermal surface plate 258 is maintained at the temperature alittle bit higher than the temperature necessary for the heat treatmentof the wafer W, the temperature affecting the wafer W is the mostsuitable temperature for the heat treatment. Accordingly, based on themeasured data, the temperatures of the thermal surface plate 258 and thejacket 290 are adjusted to stabilize at these temperatures.

More concrete, when the aimed value of the temperature of the heattreatment of the wafer W is T_(W), the temperature of the thermalsurface plate 258 is T_(H), and the temperature (the averagetemperature) of the jacket 290 is T_(L), there is a relation ofT_(L)<T_(W)<T_(H) between these T_(W), T_(L), and T_(H). In FIG. 17,this relation is depicted.

As shown in FIG. 17, by maintaining the temperature T_(H) of the heatingplate at a constant value and the temperature of the jacket 290 at thepredetermined temperature T_(L) lower than the aimed value T_(W) of theheat treatment of the wafer W, the temperature affecting the wafer W canbe maintained at the value close to the aimed value T_(W) of the heattreatment. The temperature T_(H) of the heating plate and the value ofthe temperature T_(L) thereto the jacket 290 should be maintained can beobtained based on the measured data.

Further, the temperature T_(L) thereat the jacket 290 should bemaintained may be controlled based on the temperature of the thermalsurface plate 258 detected by the temperature sensor (not shown in thefigure), or the temperature of the heating medium or the power suppliedto the heating medium supplier. Further, based on both temperatures ofthe wafer W and the thermal surface plate 258, the temperature of thejacket 290 may be controlled.

Incidentally, the present embodiment adopted a jacket 290 incorporatinga spiral circulation path 291, however, by using, other than this, acooler which is formed concentric and has a plurality of coolingportions capable of cooling to the respectively different temperaturesby the electric power, or a cooler which has a plurality ofsector-shaped cooling portions which are obtained by further dividingthe aforementioned concentric cooling portions in the diameterdirection, and of which the each part can be cooled independently, aparticular effect can be expected.

For instance, in the case of the thermal non-uniformity occurring in thehorizontal direction from the center of the thermal surface plate 258 tothe periphery portion thereof, by cooling the each sector-shaped coolingportion so as to cancel the thermal non-uniformity on the thermalsurface plate 258, the wafer W can be exposed to the uniform heattreatment.

That is, in the case of there being such a temperature gradient that thetemperature is low in the neighborhood of the center of the thermalsurface plate 258 and rises toward the periphery portion thereof, whilecooling strongly the sector-shaped cooling portions on the exteriorperiphery side, the cooling portions in the neighborhood of the centerare cooled weak, the intervening cooling portions therebetween arecooled to the intervening temperature.

On the contrary, in the case of there being such a temperature gradientthat the temperature is high in the neighborhood of the center of thethermal surface plate 258 and goes down toward the periphery portion,whereas the cooling portions in the neighborhood of the center of thecover assembly 268 are cooled strong, the cooling portions on theperiphery portion is cooled weak, and the intervening cooling potionstherebetween are cooled at the intervening temperature. Further, in thecase of the temperature being low at both the neighborhood of the centerand the periphery portion of the thermal surface plate 258, and theintervening portion between the neighborhood of the center and theperiphery portion thereof being high, only the cooling portionspositioning immediate above the portion which tends to be hightemperature are cooled strong, and the other cooling portions are cooledweak or stopped to cool.

Further, in the case of there occurring some parts of high temperatureor low temperature on the thermal surface plate 258, so as to cancel thethermal non-uniformity of that region, some of the cooling portions canbe cooled to the different temperatures from the other portions.

Next, the operation will be described for the case of the heat treatmentunit being used as a baking unit (PREBAKE) and a cooling unit (COL).

First, from inside the wafer cassette CR set on the stage 20, an wafer Wis pulled out by an wafer carrier 21, thereafter the pulled out wafer Wis delivered from the wafer carrier 21 to the main wafer carryingmechanism 22. The main wafer carrying mechanism 22 delivers and sets thedelivered wafer W into the resist coating unit (COT), where the resistcoating is carried out on the wafer W. Next, the main wafer carryingmechanism 22 pulls out the wafer W from inside the resist coating unit(COT), carries the same inside the heat treatment unit and set it on thethermal surface plate 258.

On the other hand, simultaneously with input of power to the heattreatment unit, the heating medium supplier 295 of the thermal surfaceplate 258 and a circulating system begin to operate, and, after thepredetermined time period, the thermal surface plate 258 is maintainedat the predetermined temperature, that is, at the temperature a littlebit higher than the aimed value of the temperature of the heat treatmentof the wafer W. Similarly, also to the cooling medium supplier 294 ofthe jacket 290 disposed in the central portion of the cover assembly268, the electric power is inputted to start cooling. Incidentally, inthe thermal surface plate 258 involving the present embodiment, there isa tendency that the temperature is high in the vicinity of the centerand low in the exterior periphery portion. Accordingly, so as to cancelthis, temperature control is carried out so that the heating gas(nitrogen gas) passing through the neighborhood of the center thereof iscooled by the jacket 290 disposed in the neighborhood of the center ofthe cover assembly 268.

Thus, in the heat treatment unit involving the present embodiment, uponsetting the wafer W between the thermal surface plate 258 and coverassembly 268 both of which are controlled in their amount of heat, thegas heated above the temperature of heat treatment of the wafer W by thethermal surface plate 258 tends to linger in the lower side of thevicinity of the center of the cover assembly 268. However, since thecover assembly 268 is provide with the jacket 290 in the center portion,if the temperature of the gas (nitrogen gas) passing through thisportion is above the predetermined temperature, the cooling medium iscirculated to the jacket 290 to cool the superheated gas passing throughthe lower side of the jacket 290. The cooled gas collides against theneighborhood of the center of the wafer W and prevents the temperatureof this portion from rising. Accordingly, the wafer W which is settherebetween and is exposed to heat treatment is always given uniformamount of heat, thereby the uniform heat treatment is carried out allover the wafer W.

Further, according to the heat treatment unit involving the presentembodiment, the temperature control is carried out while detecting thetemperatures of the wafer W by sensors, accordingly, a delicatetemperature control is possible, thereby the temperature control duringheat treatment of the wafer W can be carried out with high accuracy.

Incidentally, the present invention is not restricted to the content ofthe aforementioned embodiment.

For instance, in the aforementioned embodiment, description was given toa apparatus in which an wafer W is heated by use of a thermal surfaceplate which is heated uniform by circulating the heating medium insidethe same, however, a heating plate which controls the temperature by atemperature sensor or the like by incorporating a nichrome heater insidecan be employed.

According to the second invention, whereas the lower surface of thesubstrate to be treated being heated, the gas heated by a heating meansabove the predetermined temperature is cooled at the upper portion ofthe substrate to be treated, accordingly, the gas of high temperaturedoes not tend to linger at the upper portion of the substrate to betreated, thereby, all over the entire substrate to be treated theuniform heat treatment can be carried out.

In the aforementioned apparatus for heat treatment, a means fordetecting the temperature affecting the substrate to be treated may bedisposed. Based on the temperature detected by the detecting means andaffecting the substrate to be treated, the gas passing the upper portionof the substrate to be treated is cooled. Thereby, the temperaturecontrol during heat treatment of the substrate can be carried out withhigh accuracy.

Further, when the gas heated by the heating plate is cooled by thecooler disposed around the exhaust outlet of the cover assembly, the gasof high temperature does not tend to linger in the space between thesubstrate to be treated and the cover assembly, thereby all over theentire substrate to be treated uniform heat treatment can be carriedout.

Around the exhaust outlet of the cover assembly, the sensor fordetecting the temperature around there may be disposed. Based on thetemperature, detected by the sensor, of the gas in the neighborhood ofthe exhaust outlet, the heating plate and cooler are controlled.Thereby, the temperature control during the heat treatment of thesubstrate to be treated can be carried out with high accuracy.

A sensor may be disposed for detecting the temperature of the substrateto be treated. Based on the detected temperature of the substrate to betreated, the heating plate and cooler are controlled. Thereby, thetemperature control during the heat treatment of the substrate to betreated can be carried out with high accuracy.

A sensor may be disposed for detecting the temperature of the heatingplate. Based on the detected temperature of the heating plate, theheating plate and cooler are controlled. Thereby, the temperaturecontrol during the heat treatment of the substrate to be treated can becarried out with high accuracy.

The first sensor for detecting the temperature of the gas around theexhaust outlet and the second sensor for detecting the temperature ofthe heating plate may be disposed. Based on the temperatures, detectedby these sensors, of the gas around the exhaust outlet and the heatingplate, the heating plate and cooler are controlled. Thereby, thetemperature control during the heat treatment of the substrate to betreated can be carried out with high accuracy.

The first sensor for detecting the temperature of the gas around theexhaust outlet and the second sensor for detecting the temperature ofthe substrate to be treated may be disposed. Based on the temperatures,detected by these sensors, of the gas around the exhaust outlet and thesubstrate to be treated, the heating plate and cooler are controlled.Thereby, the temperature control during the heat treatment of thesubstrate to be treated can be carried out with high accuracy.

The first sensor for detecting the temperature of the gas around theexhaust outlet, the second sensor for detecting the temperature of thesubstrate to be treated and the third sensor for detecting thetemperature of the heating plate may be disposed. Based on therespective temperatures, detected by these sensors, of the gas aroundthe exhaust outlet, the substrate to be treated and the heating plate,the heating plate and cooler are controlled. Thereby, the temperaturecontrol during the heat treatment of the substrate to be treated can becarried out with high accuracy.

EXAMPLE 4

FIG. 18 is a vertical cross section of a cover assembly 368 involvingthe embodiment corresponding to the third invention, and FIG. 19 is aplan view showing a state seen from the bottom side of the coverassembly 368. As shown in FIG. 18, on the lower surface side of thecover assembly 368, a conical concave portion 368 b is formed, and at aportion corresponding to the top of the cone, an exhaust outlet 368 a isdisposed, to this exhaust outlet 368 a an lower end of an exhaustingpipe 370 is connected. The other end side of the exhausting pipe 370 isconnected the not shown exhausting system, the heating gas (air or inertgas such as nitrogen or the like) which ascended heated by the heatingplate 358 is collected at the conical concave portion 368 b andevacuated through the exhaust outlet 368 a and exhausting pipe 370.

On the side wall 368 c of the conical concave portion 368 b, a pluralityof heaters H21 through H32 are disposed forming concentric circles. Inthe cover assembly 368 involving the present embodiment, twelve sheetsof sector type heaters H21 through H32 are disposed, each four sheets ofheaters of H21 through H24, heaters H25 through H28, and heaters H29through H32 are disposed to form three concentric circles different intheir diameters, large, medium, and small. These twelve sheets ofheaters of H21 through H32 are wired so that electric power is suppliedthrough the respective control unit (not shown in the figure).

FIG. 20 is a vertical cross section showing schematically a structure ofa thermal surface plate 358 involving the present embodiment and itssurroundings. As shown in FIG. 20, the inside of the thermal surfaceplate 358 is a closed cavity 358 a, and on a part of the bottom portion,a heating medium reservoir 358 b of which the cross section is formed ina V character shape is disposed. In the heating medium reservoir 358 b,a heater such as Nichrome wire or the like 393 is disposed in adirection vertical to the plane of the paper of FIG. 20, to this heater393, electric power from the power source is supplied controlled by thecontrol unit.

Upon supplying the electric power form the power source 395 to theheater 393 after control by the control unit, the heater 393 starts toevolve heat, thereby the heating medium reserved in the heating mediumreservoir 358 b due to condensation is heated. The heated heating mediumvaporizes and circulates inside the cavity 358 a. When the vapor of theheating medium collides against the cold portion in the cavity 358 a,the heating medium gives the heat to this cold portion and at the sametime condenses to liquefy. At this time, the heating medium heats theentire interior wall of the cavity 358 a to a uniform temperature,accordingly the entire thermal surface plate is maintained at a constanttemperature.

FIG. 21 is a block diagram illustrating a control system of a heattreatment unit involving the present embodiment. As shown in FIG. 21, tothe thermal surface plate 358 an electric power supply 395 for supplyingelectric power to the heater 393 disposed within the thermal surfaceplate 358 is connected, the electric power supply 395 is controlled by acontrol unit 390 and controls the temperature of the thermal surfaceplate 358. Similarly, twelve sheets of heaters H21 through H32 are alsoconnected to the control unit 390, and turning on/off of these heatersH21 through H32 or the amount of heat of evolution of heaters H21through H32 can be controlled independently.

Next, the way of control of the heat treatment unit involving thepresent embodiment will be described.

The thermal surface plate 358 is controlled so as to maintain a constanttemperature. The temperature thereto the thermal surface plate 358 ismaintained is a temperature convenient for controlling the temperatureof heat treatment of the wafer W disposed on the thermal surface plate358, for instance, a temperature close to the heat treatment temperatureof the wafer W and a little bit lower than this heat treatmenttemperature.

In contrast to the aforementioned thermal surface plate 358 beingcontrolled so as to keep a given temperature, the heaters H21 throughH32 are maintained to such temperatures that the temperature to whichthe thermal surface plate 358 is maintained as well as the heattreatment temperature of the wafer W are maintained constant. Forinstance, it is a temperature close to the aimed value of the heattreatment temperature of the wafer W and a little bit higher than theaimed value of the temperature of the heat treatment.

In general, the aforementioned temperature of the thermal surface plateis determined based on the aimed value of the heat treatmenttemperature, and the temperatures of the heaters H21 through H32 areobtained based on the aimed value of the heat treatment temperature ofthe wafer W and the temperature of the thermal surface plate.

That is, in the case of the temperature of the thermal surface plate 358being maintained at a little bit lower temperature with respect to theaimed value of the heat treatment temperature and the wafer W beingheated from the upper surface in this state, the temperature where thetemperature actually affecting the wafer W becomes the closest to theaimed value is obtained, to these temperatures, the temperatures of theheaters H21 through H32 are controlled.

In the more concrete, when the aimed value of the temperature of theheat treatment of the wafer W is T_(W), the temperature of the thermalsurface plate 358 is T_(L), and the temperature (the averagetemperature) of the heaters H21 though H32 is T_(H), there is a relationof T_(L)<T_(W)<T_(H) between these T_(W), T_(L), and T_(H). In FIG. 22,this relation is depicted.

As shown in FIG. 22, by maintaining the temperature T_(L) of the heatingplate at a constant value and the temperature of the heaters H21 throughH32 at the predetermined temperature T_(H) higher than the aimed valueT_(W) of the temperature of the heat treatment of the wafer W, thetemperature affecting the wafer W can be maintained at the value closeto the aimed value T_(W) of the temperature of the heat treatment. Thetemperature T_(L) of the heating plate and the value of the temperatureT_(H) thereto the heaters H21 through H32 should be maintained can beobtained based on the measured data.

Incidentally, the temperature T_(H) thereto the heaters H21 through H32should be maintained may be controlled based on the temperature of thewafer W detected by the temperature sensor (not shown in the figure).

Further, in the case of the thermal non-uniformity occurring in thehorizontal direction from the central portion of the thermal surfaceplate 358 toward the periphery thereof, by heating the heaters H21through H32 so that the thermal non-uniformity on the thermal surfaceplate 358 is cancelled, the wafer W can be exposed to the uniform heattreatment.

For instance, in the case of there being such a temperature gradientthat the temperature is low in the neighborhood of the center of thethermal surface plate 358 and rises towards the periphery portion, whileheating the heaters H21 through H32 of the center of the cover assembly368 to high temperature, the heaters H29 through H32 of the exteriorperiphery are heated at low temperature, and intervening heaters H25through H28 are maintained at the intervening temperature.

On the contrary, in the case of there being such a temperature gradientthat the temperature is high in the neighborhood of the center of thethermal surface plate 358 and goes down towards the periphery portionthereof, while the heaters H21 through H24 in the center of the coverassembly 368 are heated at low temperature, the heaters H29 through H32of the exterior periphery portion are heated to high temperature, andthe intervening heaters H25 through H28 are maintained at theintervening temperature. Further, in the case of the temperature beinglow in the neighborhood of the center of this thermal surface plate 358and the periphery thereof and beings high in the intervening portion,the heaters H21 through H24 and heaters H29 through H32 are heated tohigh temperature and the heaters H25 through H28 are heated to the lowtemperature. In the case of there occurring partly high temperature orlow temperature portions due to the characteristic of the thermalsurface plate 358, so as to cancel the non-uniformity, some of theheaters H21 through H32 can be heated to the temperatures different formthe other heaters.

Further, in the present embodiment, the twelve sheets of heaters H21through H32 which are divided into sector-shape as shown in FIG. 19 areemployed, however, a so-called gradation heater which is a sheet ofcontinuous heater and can vary local heating or heating amount for eachlocal portion can be employed. In that case, while being a sheet ofcontinuous heater, it can heat locally as mentioned above. Accordingly,while maintaining the aforementioned characteristics, the number ofcomponent can be reduced or the manufacturing process can be simplified,resulting in the reduction of the manufacturing cost.

Next, the operation in the case of this heat treatment unit beingemployed as a baking unit (PREBAKE) and a cooling unit (COL) will b)edescribed in the following.

First, from inside the wafer cassette CR set on the stage 20, an wafer Wis pulled out by an wafer carrier 21, thereafter the pulled out wafer Wis delivered from the wafer carrier 21 to the main wafer carryingmechanism 22. The main wafer carrying mechanism 22 delivers and sets thedelivered wafer W into the resist coating unit (COT), where the resistcoating is carried out on the wafer W. Next, the main wafer carryingmechanism 22 pulls out the wafer W from inside the resist coating unit(COT), carries the same into the heat treatment unit and set the wafer Won the thermal surface plate 358.

On the other hand, simultaneously with input of power to the heattreatment unit, the electric power supply 395 of the thermal surfaceplate 358 begins to operate, and, after the predetermined time period,the thermal surface plate 358 is maintained at the predeterminedtemperature, that is, at the temperature a little bit lower than theaimed value of the temperature of the heat treatment of the wafer W.Similarly, also to the heaters H21 through H32 disposed on the lowersurface side of the cover assembly 368, the electric power is inputtedto start heating. Incidentally, in the thermal surface plate 358involving the present embodiment, there is a tendency that thetemperature is high in the vicinity of the center and low in theexterior periphery portion. Accordingly, in order to cancel this,temperature control is carried out so that the heating temperatures atthe heaters H21 through h24 of the cover assembly 368 are low, and asthe heaters go to the heaters H25 through H28 on the outside than theseand heaters H29 through H32 of further outside, the heating temperaturegradually goes up.

Thus, in the heat treatment unit involving the present embodiment, uponsetting the wafer W between the thermal surface plate 358 and coverassembly 368 both of which are controlled in their amount of heat, sincethe amount of heat of the heaters H21 through H32 of the cover assembly368 is controlled so as to cancel the thermal non-uniformity of theamount of heat from the thermal surface plate 358, accordingly, thewafer W which is set therebetween and is exposed to heat treatment isalways given uniform amount of heat, thereby the uniform heat treatmentis carried out all over the wafer W.

Further, since the temperatures of heaters H21 through H32 arecontrolled to be high with respect to the temperature of the thermalsurface plate 358, the thermal gradient is constituted to get highalways from the lower side toward the upper side in the verticaldirection. Therefore, the gas heated by the thermal surface plate 358ascends straight up, and there does not occur thermal convection in thespace formed between the thermal surface plate 358 and the heaters H21and H32.

Therefore, the non-uniform supply of amount of heat induced by thisthermal convection can be prevented from occurring, thereby uniform heattreatment of the wafer W is made possible.

Further, according to the heat treatment unit involving the presentembodiment, whereas the wafer W is heated from the lower surface sidewhile maintaining the thermal surface plate 358 at a relatively lowtemperature close to the lower limit for the heat treatment, thenecessary amount of heat is supplied additionally from the upper surfaceside of the wafer W by the heaters H21 through H32. Therefore, thedelicate temperature control is made, moreover, there is no possibilityof occurrence of convection due to the change of the amount of heat ofthe heaters H21 through H32. Thus, the temperature control during theheat treatment can be carried out with high accuracy.

Incidentally, the present invention is not restricted to the contents Dfthe aforementioned embodiment.

For instance, in the aforementioned embodiment, the cover assembly has ashape in which the lower surface of the cover assembly is cut in a cone,however, the shape of the lower surface can be formed in a levelsurface. In the case of the cover assembly having the lower surface ofthe level plane, there are such advantages that manufacture of the coverassembly is simple and the entire heat treatment unit can be madecompact due to the smaller cover assembly. Incidentally, in the case ofthe lower surface of the cover assembly being a level plane, byadequately combining the shape, arrangement, and capacity of evolutionof heat of the heaters H21 through H32, the thermal convection isprevented from occurring between the thermal surface plate 358 and theheaters H21 through H32.

Further, in the aforementioned embodiment, the heaters H21 through 32are disposed concentric, other than this, various arrangement such asspiral disposition can be adopted.

Similarly, in the aforementioned embodiment, the wafer W is heated byuse of the thermal surface plate which is heated uniformly bycirculating the heating medium inside, instead, a heating plate whichincorporates nichrome heater therein and controls the temperature by thetemperature sensor can be employed.

According to the third invention, while the lower surface of thesubstrate to be treated is heated to the predetermined temperature bythe first heating means, the upper surface of the substrate to betreated is heated to the temperature higher than that obtained by thefirst heating means by the second heating means, thereby such thetemperature gradient is formed in the space where the heat treatment isgiven to the substrate to be treated that the temperature rises frombelow toward above. Thus, there does not occur the thermal convectionwhich makes irregular the flow of the heating gas and the uniform heattreatment can be carried out all over the substrate to be treated.

When the temperature of heat treatment of the substrate to be treated isadjusted by controlling the second heating means which heats the uppersurface of the substrate to be treated, the flow of the heating gas isnot disturbed, thus the temperature control during the heat treatment ofthe substrate to be treated can be carried out with high accuracy.

When the second heating means is controlled so that the temperature ofheat treatment of the substrate to be treated becomes the aimedtemperature by further use of the aforementioned means for detecting thetemperature of the substrate to be treated, based on the actuallydetected temperature of the substrate to be treated, the temperaturecontrol during the heat treatment of the substrate to be treated can becarried out with high accuracy.

While heating the lower surface of the substrate to be treated to thepredetermined temperature by use of the heating plate, the upper surfaceof the substrate to be treated is heated to the temperature higher thanthe heating plate by use of the heaters. Thus, in the space where theheat treatment is carried out to the substrate to be treated, such atemperature gradient is formed that the temperature rises from belowtoward above. Thereby, the thermal convection which makes irregular theflow of the heating gas does not occur in this space, the uniform heattreatment can be carried out all over the substrate to be treated.Further, when the heaters are adjusted by the second control portion tothe temperature where the substrate to be treated is treated at theaimed temperature, the flow of the heating gas is not disturbed,resulting in the highly accurate temperature control during the heattreatment of the substrate to be treated.

In the aforementioned apparatus of heat treatment, if such a heater isadopted that is divided into a plurality of heaters capable of turningon and off the electric power source independently, a delicatetemperature control can be carried out, resulting in the further highlyaccurate temperature control during the heat treatment of the substrateto be treated.

What is claimed is:
 1. A heat treatment apparatus, which comprises: aheat treatment table thereon a substrate to be treated is disposed; twoor more of heaters heating each regions obtained by dividing the heattreatment table into two or more; at least one sensor detectingtemperature of the predetermined portion of the heat treatment table; ameans for surmising the temperature of each portions of the heattreatment table based on the detected temperature; and a means forcontrolling output of the each heaters based on the detected temperatureso that the temperature of the entire heat treatment table is uniform;wherein each of the heaters disposed on the heat treatment table aredisposed concentric, and sensors are disposed in a thickness direction.2. The heat treatment apparatus as set forth in claim 1: wherein themeans for surmising the temperature is an arithmetic unit which isconnected to the sensor and, based on the detected temperature, surmisesmathematically the temperatures of the each portions of the heattreatment table; wherein the controlling means is a control unit whichis connected to the arithmetic unit and, based on the surmisedtemperatures of the each portions, controls the output of the eachheaters so that the temperature of the entire heat treatment table isuniform.
 3. A heat treatment apparatus, which comprises: a heattreatment table thereon a substrate to be treated is disposed; two ormore of heaters heating each regions obtained by dividing the heattreatment table into two or more regions; at least one sensor detectingtemperature of the predetermined portion of the heat treatment table; ameans for surmising amount of heat supplied to each portions of thesubstrate to be treated based on the detected temperature; and a meansfor controlling output of the each heaters based on the surmised amountof heat so that the amount of heat supplied to the substrate to betreated is uniform; wherein each of the heaters disposed on the heattreatment table are disposed concentric, and sensors are disposed in athickness direction.
 4. The heat treatment apparatus as set forth inclaim 3: wherein the means for surmising the temperature is anarithmetic unit which is connected to the sensor and, based on thedetected temperature, surmises mathematically the amount of heatsupplied to the each portions of the substrate to be treated; whereinthe controlling means is a control unit which is connected to thearithmetic unit and, based on the surmised temperatures of the eachportions, controls the output of the each heaters so that the amount ofheat supplied to the substrate to be treated is uniform.
 5. The heattreatment apparatus as set forth in claim 1, further comprises: a coverassembly which is disposed opposite to the heat treatment table abovethe heat treatment table and evacuates a gas heated by the heattreatment table; wherein, on the surface opposite to the heat treatmenttable of the cover assembly, a plurality of upper heaters are disposeddivided concentric.
 6. The heat treatment apparatus as set forth inclaim 3, which further comprises: a cover assembly which is disposedopposite to the heat treatment table above the heat treatment table andevacuates a gas heated by the heat treatment table; wherein, on thesurface opposite to the heat treatment table of the cover assembly, aplurality of upper heaters are disposed divided concentric.
 7. The heattreatment apparatus as set forth in claim 1: wherein thus each heatersdisposed to the heat treatment table are disposed concentric, andsensors are disposed in one line in a diameter direction of the heattreatment table.
 8. The heat treatment apparatus as set forth in claim1: wherein the each heaters disposed on the heat treatment table aredisposed concentric, and sensors are disposed in one line in a diameterdirection and in a thickness direction.
 9. The heat treatment apparatusas set forth in claim 3: wherein the each heaters disposed to the heattreatment table are disposed concentric, and sensors are disposed in oneline in a diameter direction.
 10. The heat treatment apparatus as setforth in claim 3: wherein the each heaters disposed on the heattreatment table are disposed concentric, and sensors are disposed in oneline in a diameter direction and in a thickness direction.
 11. The heattreatment apparatus set forth in claim 1, further comprising: a firstheating means for heating a lower surface of a substrate to be treatedto a predetermined temperature; and a second heating means for heatingan upper surface of the substrate to be treated at a temperature higherthan the first heating means.
 12. The heat treatment apparatus as setforth in claim 11, which further comprises: a means for controlling thesecond heating means to a temperature where the substrate to be treatedis exposed to heat treatment at an aimed temperature.
 13. The heattreatment apparatus as set forth in claim 12, which further comprises: ameans for detecting the temperature of the substrate to be treated;wherein the controlling means is a means for controlling the secondheating means, based on the detected temperature of the substrate to betreated, so that a temperature of heat treatment of the substrate to betreated is an aimed temperature.
 14. The heat treatment apparatus as setforth in claim 12: wherein the first heating means is a heating platethereon a substrate to be treated is disposed, and which comprisesfurther a cover assembly which is disposed opposite to the heating plateabove the heating plate and evacuates a gas heated by the heating plate;the second heating means is at least one heater disposed on a surface ofthe cover assembly opposed to the heating plate; and the controllingmeans comprises a first control unit for maintaining the heating plateat a predetermined temperature, and a second control unit for adjustingthe heater to a temperature which is higher than the heating plate andunder which the substrate to be treated is treated at an aimedtemperature.
 15. The heat treatment apparatus as set forth in claim 12:wherein the first heating means is a heating plate thereon a substrateto be treated is disposed, and which comprises further a cover assemblywhich is disposed opposite to the heating plate above the heating plateand evacuates a gas heated by the heating plate, and a sensor fordetecting the temperature of the substrate to be treated; the secondheating means is at least one heater disposed on a surface of the coverassembly opposed to the heating plate; and the controlling meanscomprises a first control unit for maintaining the heating plate at apredetermined temperature, and a second control unit for adjusting theheater, based on the detected temperature of the substrate to betreated, to a temperature which is higher than the heating plate andunder which the substrate to be treated is treated at an aimedtemperature.
 16. The heat treatment apparatus as set forth in claim 14:wherein the at least one heater of the second heating means divided intoa plurality of heaters capable of turning on and off an electric powersource independently.
 17. The heat treatment apparatus as set forth inclaim 14: wherein the at least one heater of the second heating means isdisposed concentric.
 18. The heat treatment apparatus as set forth inclaim 17: wherein the at least one heater of the second heating means isdivided into two or more parts along a diameter direction.
 19. The heattreatment apparatus as set forth in claim 14: wherein the at least oneheater of the second heating means is a gradation heater of whichheating capacity is continuously inclined from the center of the coverassembly to the periphery portion.
 20. The heat treatment apparatus asset forth in claim 14: wherein the heating plate is a thermal surfaceplate which maintains a predetermined temperature by heating mediumvapor circulating inside thereof.
 21. The heat treatment apparatus asset forth in claim 14: wherein, on a lower surface side of the coverassembly, a flat surface opposite to the heating plate is formed. 22.The heat treatment apparatus as set forth in claim 8: wherein the meansfor surmising the temperature is an arithmetic unit which is connectedto the sensor and, based on the detected temperature, surmisesmathematically the temperatures of the each portions of the heattreatment table; wherein the controlling means is a control unit whichis connected to the arithmetic unit and, based on the surmisedtemperatures of the each portions, controls the output of the eachheaters so that the temperature of the entire heat treatment table isuniform.
 23. The heat treatment apparatus as set forth in claim 8:wherein each of the heaters disposed to the heat treatment table aredisposed concentric, and sensors are disposed in one line in a diameterdirection of the heat treatment table.
 24. The heat treatment apparatusas set forth in claim 10: wherein the means for surmising thetemperature is an arithmetic unit which is connected to the sensor and,based on the detected temperature, surmises mathematically the amount ofheat supplied to the each portions of the substrate to be treated;wherein the controlling means is a control unit which is connected tothe arithmetic unit and, and based on the surmised temperatures of theeach portions, controls the output of the each heaters so that theamount of heat supplied to the substrate to be treated is uniform. 25.The heat treatment apparatus as set forth in claim 10: wherein each ofthe heaters disposed to the heat treatment table are disposedconcentric, and sensors are disposed in one line in a diameterdirection.
 26. The heat treatment apparatus set for the in claim 3,further comprising: a first heating means for heating a lower surface ofa substrate to be treated to a predetermined temperature; and a secondheating means for heating an upper surface of the substrate to betreated at a temperature higher than the first heating means.
 27. Theheat treatment apparatus as set forth in claim 26, which furthercomprises: a means for controlling the second heating means to atemperature where the substrate to be treated is exposed to heattreatment at an aimed temperature.
 28. The heat treatment apparatus asset forth in claim 27, which further comprises: a means for detectingthe temperature of the substrate to be treated; wherein the controllingmeans is a means for controlling the second heating means, based on thedetected temperature of the substrate to be treated, so that atemperature of heat treatment of the substrate to be treated is an aimedtemperature.
 29. The heat treatment apparatus as set forth in claim 27:wherein the first heating means is a heating plate thereon a substrateto be treated is disposed, and which comprises further a cover assemblywhich is disposed opposite to the heating plate above the heating plateand evacuates a gas heated by the heating plate; the second heatingmeans is at least one heater disposed on a surface of the cover assemblyopposed to the heating plate; and the controlling means comprises afirst control unit for maintaining the heating plate at a predeterminedtemperature, and a second control unit for adjusting the heater to atemperature which is higher than the heating plate and under which thesubstrate to be treated is treated at an aimed temperature.
 30. The heattreatment apparatus as set forth in claim 27: wherein the first heatingmeans is a heating plate thereon a substrate to be treated is disposed,and which comprises further a cover assembly which is disposed oppositeto the heating plate above the heating plate and evacuates a gas heatedby the heating plate, and a sensor for detecting the temperature of thesubstrate to be treated; the second heating means is at least one heaterdisposed on a surface of the cover assembly opposed to the heatingplate; and the controlling means comprises a first control unit formaintaining the heating plate at a predetermined temperature, and asecond control unit for adjusting the heater, based on the detectedtemperature of the substrate to be treated, to a temperature which ishigher than the heating plate and under which the substrate to hetreated is treated at an aimed temperature.
 31. The heat treatmentapparatus as set forth in claim 29: wherein the at least one heater ofthe second heating means is divided into a plurality of heaters capableof turning on and off an electric power source independently.
 32. Theheat treatment apparatus as set forth in claim 29: wherein the at leastone heater of the second heating means is disposed concentric.
 33. Theheat treatment apparatus as set forth in claim 32: wherein the at leastone heater of the second heating means is divided into two or more partsalong a diameter direction.
 34. The heat treatment apparatus as setforth in claim 29: wherein the at least one heater of the second heatingmeans is a gradation heater of which heating capacity is continuouslyinclined from the center of the cover assembly to the periphery portion.35. The heat treatment apparatus as set forth in claim 29: wherein theheating plate is a thermal surface plate which maintains a predeterminedtemperature by heating medium vapor circulating inside thereof.
 36. Theheat treatment apparatus as set forth in claim 29: wherein, on a lowersurface side of the cover assembly, a flat surface opposite to theheating plate is formed.